Gold is a simple form of chemical element gold (Au), which is a soft, golden yellow and corrosion-resistant precious metal. Gold is one of the rarer, more precious and highly valued metals. Generally, gold in the world is measured in ounces. In ancient China, gold was measured in ounces, which is a very important metal. It is not only a special currency for reserve and investment, but also an important material for jewelry industry, electronics industry, modern communication and aerospace industry.